GM Service Manual Online
For 1990-2009 cars only

Service of the PCM should normally consist of replacement of the PCM.

If the diagnostic procedures call for replacing the PCM, peform the following procedures in the following order:

  1. Programming the PCM
  2. Passlock Learn Procedure
  3. Programming the TDC Offset

Removal Procedure


    Object Number: 26961  Size: SH

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Remove the negative battery cables.
  2. Remove the PCM from the passenger compartment behind the glove box.
  3. Remove the connectors from the PCM.
  4. Important: To prevent possible electrostatic discharge to the PCM, do not touch the component leads, and do not remove the integrated circuit from the carrier.

  5. Remove the PCM mounting hardware.

Installation Procedure


    Object Number: 26961  Size: SH
  1. Install the PCM mounting hardware.
  2. Install the connectors to the PCM.
  3. Install the PCM in the passenger compartment behind the glove box.
  4. Install the negative battery cables.
  5. The MIL, antilock and brake lamps will continue to be enabled until the PCM is programmed. Once the programming is complete, the lamps will turn OFF and normal operation will occur.

  6. Refer to PCM Programming.

PCM Programming

  1. Verify the following for the setup:
  2. • The battery is charged.
    • The ignition is ON.
    • The battery/cig. lighter connection is secure.
    • The Data Link Connector is attached.
  3. Perform the programming. Refer to the up to date Techline terminal/equipment for user instructions.
  4. Perform the Passlock Learn Procedure. Refer to Password Learn .
  5. After the vehicle has been programmed, operate the vehicle until the coolant temperature is greater than 77°C (170°F). This will allow the TDC Offset to be programmed (refer to Programming the TDC Offset ).
  6. Check the Data list for a TDC Offset.
  7. If the PCM fails to reprogram, do the following:
  8. • Check all the PCM connections.
    • Check the Techline terminal/equipment for the latest software version.
    • Try again to reprogram the PCM. If it fails again, replace the PCM. Refer to PCM replacement.

Programming the TDC Offset

The PCM will automatically activate the TDC Offset program when the engine coolant is greater than 77°C (170°F). If the PCM is not programmed with a TDC Offset, a DTC P1214 will set.